1. Field of the Invention
The present invention relates to an airbag for use in motor vehicles. In particular it relates to a side airbag which uses a guide member to stabilize the flow of gas emitted from a gas generator into the airbag.
2. Description of Related Art
An airbag installed on the sides of the interior of a vehicle passenger compartment, and in particularly extended from the front seat region to the rear seat region, is commonly called a “side airbag” or “curtain airbag” in the art. When a side impact occurs, gas inflates the airbag which then expands, drops down from the passenger compartment ceiling, and covers the window, much like a curtain, in order to protect the passenger from injury. An airbag utilizing this type of structure is formed from one piece of fabric-like material folded over on itself, or two mutually overlaid fabric layers, after which the pieces of material are joined by adhering, welding, or sewing to form a bag-like structure.
In a conventional curtain-type automotive airbag device, inflating gas simply enters the airbag at the opening in the airbag where the insertion end of the gas generator is attached, the gas flow into the airbag only being controlled by the partitions formed at the seams where the fabric layers have been joined. This operation results in the adverse effect of an unstable gas flow within the airbag in the periphery of the insertion end of the gas generator, and thus indicates an area where the design of the airbag can be improved.
A countermeasure applied to rectify this problem has been to install a specially designed gas guide member in the airbag and to attach it to the insertion end of the gas generator as means of separating or directing the gas in specific directions therethrough. It has been assumed that the gas guide member may be made from the same flexible material as the airbag in order to be able to install the airbag to the vehicle body in the form of a rolled up spiral or folded over configuration.
It has been determined, however, that forming the gas guide member from a soft material results in the gas guide member vibrating with unstable oscillations due to the pressure of the flowing gas. This vibration has a destabilizing effect on the gas flow direction, and thus defeats the purpose of the gas guide member. Moreover, the high temperature gas may damage the airbag seams, especially those seams placed in proximity to the insertion end of the gas generator. These factors have the potential to adversely affect the performance and dependability of airbag operation.
In consideration of the aforesaid shortcoming of the conventional airbag structure, it is apparent there exists a need for an automotive airbag incorporating an improved gas guide member, to stabilize the flow of gas into the airbag.